Exercise bike



FIG. 1 is a top, front, left perspective view of an exercise bike showing our new design;

FIG. 2 is front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof;

FIG. 8 is a top, rear, left perspective view thereof; and,

FIG. 9 is a top, rear, right perspective view thereof.

The broken lines immediately adjacent to the shaded area define the bounds of the claimed design and form no part thereof. The broken lines depicting the remainder of the exercise bike show features that form no part of the claimed design. 

CLAIM The ornamental design for an exercise bike, as shown and described. 